|Male Wilson's Warbler|
We have a tendency to think of the birds that pass through NW Ohio in the spring and fall as "our birds." Of course, some of them will stay in Ohio to breed, but the majority spend most of their time elsewhere, either breeding, during migration, or wintering in some habitat south of the U.S. border.
|Chestnut-sided Warbler still in basic plumage|
|Summer Tanager male molting into Alternate Plumage|
One discovery that still stands out for me was when we weighed Chestnut-sided Warbler at the Tortuguero site. It had no fat and weighed 6.8 grams. This was a bit of a shock to me, since when we capture them here in Ohio during migration, they do have some amount of fat reserves and usually weigh around 8-9 grams. I was concerned the scale to weigh the birds was not working correctly, but it was checked and was calibrated properly. So, was the CSWA at a normal weight for the wintering area? What happens when it is time to migrate? Is the habitat good enough to build fat reserves for migration? Is there a critical level of volume or quality of habitats to provide enough food resources for them to make a long distance migration?
|Tennessee Warbler in the cloud forest mountains of CR|
|Black-and-white Warbler Male|
|Louisiana Waterthrush captured in the fragmented areas of the cloud forest|